The plastic genome: The impact of transposable elements on gene functionality and genomic structural variations

Abstract

Transposable elements (TEs) are DNA sequences that can change their position within genomes. TEs are present in most organisms and can be an important genomic component. Their activities are manifold: restructuring of genome size, chromosomal rearrangements, induction of gene mutations, and alteration of gene activity by insertion near or within promoters, intronic regions, or enhancer. There are several examples of mutations and other genetic variations determined by the activity of TEs, associated with the evolution of prokaryotic and eukaryotic organisms and the domestication of plants. Generally, TE mobilization occurs when the organism is subjected to stress, which can include both biotic and abiotic stresses, polyploidy conditions, and interspecific hybridizations, very common events in plants. TEs are widely distributed among organisms. TEs also play essential roles in evolution, but most of them are either dormant or inactive. This is mainly determined by epigenetic silencing mechanisms, regulatory systems, and control systems that aim to limit its proliferation. Furthermore, the host has recruited many genes originated from TEs as transcriptional regulators, especially in defense against pathogens and invasive genetic elements; this phenomenon is called molecular domestication. Therefore, TEs are responsible for horizontal gene transfer and the movement of genetic material between organisms, even phylogenetically distant, with a consequent remixing of their gene pools.

Transposable Elements and Human Diseases: Mechanisms and Implication in the Response to Environmental Pollutants

“…In plants and animals, different forms of stress are known to act as triggers or facilitators of TE mobility [140,141]. Several studies in plants have reported overexpression of TEs following abiotic or biotic stress conditions such as temperature, nitrate de-privation, and wounding [142][143][144][145]. Activation of TEs in response to different stresses has also been demonstrated in insects [146], and especially in the context of insecticide resistance [147][148][149].…”

Evolution of Diverse Strategies for Promoter Regulation

“…Significantly, active transposable elements can increase the size of the genome and facilitate rapid genetic adaptation to stressful environments [88]. Transposition activity can have positive and negative influences on gene expression and strong promoters from viruses and transposable elements contribute to the rapid genetic diversity of primates [89] and many plant species [90,91]. It is also of note that stable and conserved G-quadruplexes are located in the long terminal repeat (LTR) promoter of retroviruses [92] and human herpesviruses immediate-early promoters [58].…”

Multidisciplinary of anti-COVID-19 battle: from immunological weapons to ecological interventions

“…Not only has the human genome evolved in relation to its symbiotic microorganisms (and vice versa), but important portions of the human genome are made up of viral vestiges. From exogenous elements, these components have become integral parts of the genome, modifying its functionality and expressive possibilities [14,15,21,22,25,26,28,29,32,33].…”